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Global warming must not exceed 1.5C, warns landmark UN report
by IPCC, Union of Concerned Scientists, news agencies
12:55pm 8th Oct, 2018
Oct. 2018
Global warming must not exceed 1.5C, warns landmark UN report. (Guardian International)
In a stark new warning, the world’s leading climate scientists have shown that global warming must be kept to a maximum of 1.5C to lessen the risk of drought, floods, extreme heat and poverty for hundreds of millions of people.
The authors of the landmark report by the UN Intergovernmental Panel on Climate Change (IPCC) released on Monday say urgent and unprecedented changes are needed to reach the target, which they say is affordable and feasible although it lies at the most ambitious end of the Paris agreement pledge to keep temperatures between 1.5C and 2C.
The half-degree difference could also prevent corals from being completely eradicated and ease pressure on the Arctic, according to the 1.5C study, which was launched in Incheon in South Korea after approval at a final plenary of all 195 countries that saw delegates hugging one another, with some in tears.
“It’s a line in the sand and what it says to our species is that this is the moment and we must act now,” said Debra Roberts, a co-chair of the working group on impacts. “This is the largest clarion bell from the science community and I hope it mobilises people and dents the mood of complacency.”
Policymakers commissioned the report at the Paris climate talks in 2016, but since then the gap between science and politics has widened. Donald Trump has promised to withdraw the US – the world’s biggest source of historical emissions – from the accord. There were fears that the first round of Brazil’s presidential election would put Jair Bolsonaro into a strong position to carry out his threat to do the same and also open the Amazon rainforest to agribusiness.
The world is currently 1C warmer than preindustrial levels. Following devastating hurricanes in the US, record droughts in Cape Town and forest fires in the Arctic, the IPCC makes clear that climate change is already happening and warns that every fraction of additional warming will worsen the impact.
Scientists who reviewed the 6,000 works referenced in the report, said the change caused by just half a degree came as a revelation. “We can see there is a difference and it’s substantial,” Roberts said.
At 1.5C the proportion of the global population exposed to water stress could be 50% lower than at 2C, it notes. Food scarcity would be less of a problem and hundreds of millions fewer people, particularly in poor countries, would be at risk of climate-related poverty.
At 2C extremely hot days, such as those experienced in the northern hemisphere this summer, would become more severe and common, increasing heat-related deaths and causing more forest fires.
But the greatest difference would be to nature. Insects, which are vital for pollination of crops, and plants are almost twice as likely to lose half their habitat at 2C compared with 1.5C. Corals would be 99% lost at the higher of the two temperatures, but more than 10% have a chance of surviving if the lower target is reached.
Sea-level rise would affect 10 million more people by 2100 if the half-degree extra warming brought a forecast 10cm additional pressure on coastlines. The number affected would increase substantially in the following centuries due to locked-in ice melt.
Oceans are already suffering from elevated acidity and lower levels of oxygen as a result of climate change. One model shows marine fisheries would lose 3m tonnes at 2C, twice the decline at 1.5C.
Sea ice-free summers in the Arctic, which is warming two to three times fast than the world average, would come once every 100 years at 1.5C, but every 10 years with half a degree more of global warming.
Time and carbon budgets are running out. By mid-century, a shift to the lower goal would require a supercharged roll-back of emissions sources that have built up over the past 250 years.
The IPCC maps out several pathways to achieve 1.5C, with different combinations of land use and technological change. Reforestation is essential to all of them as are shifts to electric transport systems and greater adoption of carbon capture technology.
Carbon pollution would have to be cut by 45% by 2030 – compared with a 20% cut under the 2C pathway – and come down to zero by 2050, compared with 2075 for 2C. This would require carbon prices that are three to four times higher than for a 2C target. But the costs of doing nothing would be far higher.
“We have presented governments with pretty hard choices. We have pointed out the enormous benefits of keeping to 1.5C, and also the unprecedented shift in energy systems and transport that would be needed to achieve that,” said Jim Skea, a co-chair of the working group on mitigation. “We show it can be done within laws of physics and chemistry. Then the final tick box is political will. We cannot answer that. Only our audience can – and that is the governments that receive it.”
He said the main finding of his group was the need for urgency. Although unexpectedly good progress has been made in the adoption of renewable energy, deforestation for agriculture was turning a natural carbon sink into a source of emissions. Carbon capture and storage projects, which are essential for reducing emissions in the concrete and waste disposal industries, have also ground to a halt.
Reversing these trends is essential if the world has any chance of reaching 1.5C without relying on the untried technology of solar radiation modification and other forms of geo-engineering, which the IPCC says may not work and could have negative consequences.
Bob Ward, of the Grantham Research Institute on Climate Change, said the final document was “incredibly conservative” because it did not mention the likely rise in climate-driven refugees or the danger of tipping points that could push the world on to an irreversible path of extreme warming.
The report will be presented to governments at the UN climate conference in Poland at the end of this year. But analysts say there is much work to be done, with even pro-Paris deal nations involved in fossil fuel extraction that runs against the spirit of their commitments. Britain is pushing ahead with gas fracking, Norway with oil exploration in the Arctic, and the German government wants to tear down Hambach forest to dig for coal.
At the current level of commitments, the world is on course for a disastrous 3-4C of warming. The report authors are refuseing to accept defeat, believing the increasingly visible damage caused by climate change will shift opinion their way.
“I hope this can change the world,” said Jiang Kejun of China’s semi-governmental Energy Research Institute, who is one of the authors. “Two years ago, even I didn’t believe 1.5C was possible but when I look at the options I have confidence it can be done. I want to use this report to do something big in China.”
There is more awareness among the population about the problem of rising temperatures. “People in Beijing have never experienced so many hot days as this summer. It’s made them talk more about climate change.”
Regardless of the US and Brazil, he said, China, Europe and major cities could push ahead. “We can set an example and show what can be done.”
James Hansen, the former Nasa scientist who helped raised the alarm about climate change, said both 1.5C and 2C would take humanity into uncharted and dangerous territory because they were both well above the Holocene-era range in which human civilisation developed. But he said there was a huge difference between the two: “1.5C gives young people and the next generation a fighting chance of getting back to the Holocene or close to it. That is probably necessary if we want to keep shorelines where they are and preserve our coastal cities.”
Johan Rockström, a co-author of the recent Hothouse Earth report, said scientists never previously discussed 1.5C, which was initially seen as a political concession to small island states. But he said opinion had shifted in the past few years along with growing evidence of climate instability and the approach of tipping points that might push the world off a course that could be controlled by emissions reductions.
“Climate change is occurring earlier and more rapidly than expected. Even at the current level of 1C warming, it is painful,” he told the Guardian. “This report is really important. It has a scientific robustness that shows 1.5C is not just a political concession. There is a growing recognition that 2C is dangerous.”
Oct 7, 2018
IPCC Report: 1.5 Degrees Global Warming means Worsening Droughts, Extreme Weather and Damage. Another half-degree Celsius will dramatically increase risks to people and ecosystems they depend on. (InsideClimate News)
Without a radical transformation of energy, transportation and agriculture systems, the world will hurtle past the 1.5 degree Celsius target of the Paris climate agreement by the middle of the century, according to a new report from the Intergovernmental Panel on Climate Change.
Failing to cap global warming near that threshold dramatically increases risks to human civilization and the ecosystems that sustain life on Earth, according to the latest IPCC report.
To keep warming under 1.5°C, countries will have to cut global CO2 emissions 45 percent by 2030 and reach net zero by around 2050, the report found, re-affirming previous conclusions about the need to end fossil fuel burning. Short-lived climate pollutants, such as methane, will have to be significantly reduced as well.
More than 1.5°C warming means nearly all of the planet''s coral reefs will die, droughts and heat waves will continue to intensify, and an additional 10 million people will face greater risks from rising sea level, including deadly storm surges and flooded coastal zones. Most at risk are millions of people in less developed parts of the world, the panel warned.
The report is a follow-up to the 2015 Paris Agreement and shows how climate risks to society will dramatically increase if the average global temperature rises more than 1.5°C above pre-industrial levels. Through 2017, the buildup of greenhouse gases in the atmosphere had already warmed the world by about 1°C.
"Currently, we are on pace to blow past 1.5 degrees Celsius in a couple decades," said Pennsylvania State University climate scientist Michael Mann. Even under the current base-case scenario, with the emissions cuts pledged in Paris, the world is on track to warm between 3 and 4 degrees Celsius, he said.
"Every half-degree matters, and 2 degrees Celsius and 1.5C warming shouldn''t be thought of as cliffs we walk off. A better analogy is a minefield. The further out on to that minefield we go, the more explosions we are likely to set off," he said.
In particular, the new report spells out the difference between warming 1.5°C and 2°C, based on thousands of new scientific research papers published during the past few years.
The scientific research underlying the report is more certain than ever that the risk of extreme and deadly heat waves increases. The increase from 1.5°C to 2°C pushes extreme heat events past the upper limit of variability and a new climate regime, particularly in tropical regions. It also suggests that:
Risks from extreme precipitation events would increase dramatically with 2°C warming, especially in eastern Asia and eastern North America. Sea level would rise about 4 inches more with 2°C of warming than with 1.5°C, affecting 10 million more people. An extra 580,000 to 1 million square miles of permafrost would thaw at 2°C compared to 1.5°C. At 1.5°C of warming, the Arctic is forecast to be ice-free once per century; at 2°C warming, that would happen once every 10 years.
What''s Missing from the IPCC Report?
Despite these projections, some groups closely watching the process say the final version of the report—which had to be approved by all 195 IPCC member nations—doesn''t do enough to warn world leaders about the grim consequences of reaching potential climate tipping points that could trigger conflicts over resources and mass migration.
"I was a reviewer on an earlier draft and was concerned that it left out some of the most important risks governments need to be aware of," said Bob Ward, policy and communications director for the Grantham Research Institute on Climate Change and the Environment.
"There was no mention of the potential for conflicts and mass displacement of people, which is of huge concern to governments. There wasn''t much mention of tipping points. The IPCC has a reputation of not describing high-impact, low-probability events. There is evidence we may have already passed some key climate thresholds, including a meltdown of the West Antarctic Ice Sheet, which would raise sea level several meters in the next few centuries," he said.
There''s also a growing risk that warming will disrupt key ocean circulations, including currents that keep Europe mild despite its relatively high latitude, Ward said. That could have dramatic consequences, including a Scandinavian-like climate for temperate parts of Western Europe.
"Those concerns have been documented very clearly the last few years. It would be inexplicable if you don''t talk about some of these biggest risks in the summary for policymakers," he said.
Numbers from the International Federation of Red Cross and Red Crescent Societies provide a solid foundation for those concerns: weather-related events displaced 23.5 million people in 2016. IFRC President Francesco Rocca said half of the organization''s operations are in response to weather-related disasters, which are compounded by "climate shocks and stresses."
"It is difficult to comprehend the scale of crises confronting vulnerable communities in a world that is 1.5°C or 2.0°C hotter," he said in a statement reacting to the IPCC report.
University of Florida sea level rise expert Andrea Dutton said she hopes the new report will help clarify global warming threats for the public, especially the risk of sea level rise in coastal areas.
"What sounds like small increments in temperature can have devastating effects in terms of climate impacts on growing human populations," she said. "This report is not about whether the planet can withstand another half-degree increase in temperature. It is about understanding whether we can withstand it. Small temperature changes can have far-reaching impacts on our ability to survive on this planet."
Satellite measurements from recent years show sea level rising faster than expected, and new data from ancient ice layers, tree rings and other sources suggest the polar ice sheets are more vulnerable to extensive melting at 1.5°C warming than previously believed.
"So, it is all doom and gloom? No, because every increment of progress we can make to keep the temperature from climbing even higher will make a difference," Dutton said. "The steps that need to be taken to abate the worst outcomes require leadership at every level. My hope is that this report will encourage and empower that leadership."
Existing pledges to cut greenhouse gas emissions submitted under the Paris Agreement don''t come close to limiting global warming to 1.5°C, or even 2°C; scientists say they would result in closer to 3 or 4°C of warming. To stay under 1.5°C warming without relying on unproven CO2 removal technology means CO2 emissions must be cut in half by 2030, according to the report.
The report should be a wakeup call to the world to start acting now, said Bill Hare, CEO of Climate Analytics, a climate science and policy think tank.
"This report shows that dealing with climate change will become more dangerous and more expensive the longer we wait. Governments must get ready to commit to much more aggressive climate targets by 2020 at the latest, and they have to ditch coal," he said.
According to the IPCC, renewable energy must make up more than half the global energy mix by 2050, and coal needs to be almost completely phased out by then.
Failing that, the world will have to remove large quantities of CO2 from the atmosphere in the second half of the century. If the average global temperature overshoots 1.5°C warming by just 0.2 degrees, CO2 removal would have to be deployed at a scale "that might not be achievable given considerable implementation challenges," the report says.
The new IPCC report will be key to discussions in Katowice, Poland, in December, when the world meets for the annual UN climate talks to try to finalize the rules for implementing the Paris Agreement.
Christopher Weber, global lead scientist for climate and energy for the World Wildlife Fund, said negotiators in Poland should focus on the underlying science.
"This is not a political negotiation, it''s a science report. We''re already seeing impacts like super storms, wildfires and heat waves from 1 degree of warming," he said. "This report underscores that many of the impacts we thought we would see at 2 degrees we will see sooner, and they may be unstoppable above that." IPCC Summary (34pp):

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